Go to the Priorites sub-menu and adjust accordingly until you get it right. The idea is to boot the USB stick in UEFI first, and if that fails, try to boot USB stick normally, and if that fails, boot your SSD/CFast device as a last resort. This is a picture of my seutp which is slightly different. Your BIOS should point to your SSD instead.

Exit and Save

Once you have made the necessary adjustments outlined above, go to the last menu "Save And Exit", save your settings and reboot.

From this moment on, when you plug in the LiveCD USB stick, your computer will automatically boot into the LiveCD. But after installation and when you remove the USB stick, your computer will boot into your selected SSD/CFast storage instead.